Analysis of Listeria monocytogenes Strain Distribution in a Pork Slaughter and Cutting Plant in the Province of Quebec

Abstract

Following the 2008 Canadian listeriosis outbreak associated with ready-to-eat (RTE) meat products, regulations on the presence of Listeria monocytogenes in RTE food production facilities were modified by Health Canada, confirming the need to control this pathogen, not only in the final product but also in the plant environment. Information on the occurrence of this microorganism during the early steps of production, such as the slaughtering process and in the cutting area, is scarce in Canada. In this study, we sampled different production steps in a slaughtering and cutting plant in the province of Quebec over a 2-year period. The lairage pens, representative areas of the slaughter line, and cutting zones were targeted after their respective cleaning procedures. A total of 874 samples were analyzed for the presence of L. monocytogenes. Characterization was done by first genoserogrouping the isolates using multiplex PCR and then using a pulsed-field gel electrophoresis approach. L. monocytogenes was detected throughout all production stages. The 108 positive samples found were analyzed further, and we established that there were 4 different serogroups, with serogroup IIb being the most prevalent. The results of pulsed-field gel electrophoresis analysis showed a significant decrease in the diversity of strains from the first areas of the plant to the cutting room (10 pulsotypes in 13 positive samples in lairage and 9 in 86 positive samples in cutting) and also showed the overrepresentation of a single predominant strain in the cutting room environment (type 1, representing 96.1% of the isolates). Biofilm formation analysis of the strains cannot exclusively explain the transitions we observed. A strong genotypic similarity between strains isolated in the early production areas and some strains in the cutting room was shown. These results support the need for better surveillance of L. monocytogenes prior to RTE food production in order to design control strategies that are better adapted from a public health perspective.

Characterisation of InlA truncation in Listeria monocytogenes isolates from farm animals and human cases in the province of Quebec

“…The virulence analysis tools used in this study ( inl A sequencing and C elegans model) on both confirmed virulent and presumed less virulent strains could not univocally established the public health risk associated with L monocytogenes strains. No pig clinical case strains were provided by the MAPAQ laboratory, but serovar 4b strains were previously found in the collection of strains from healthy pigs in primary production (Larivière-Gauthier and others 2014). As calls for farm to fork strain traceability continue to be made, accurate surveillance is needed to enlarge the collection of strains in animal surveillance, particularly from pig production.…”

“…The collection was completed with four strains of pig origin isolated in a previous project (Larivière-Gauthier and others 2014). These strains showed a single nucleotide polymorphism (SNP) premature stop codon in the inlA sequence (Pulso1 and Pulso9 strains) or an integrated inlA sequence (Pulso4 and Pulso6 strains).…”

The fecal presence of enterotoxin and F4 genes as an indicator of efficacy of treatment with colistin sulfate in pigs

“…The genes encoding STa, STb, LT, F4 were detected by multiplex PCR using published primers [13, 14]. Multiplex PCR positive and negative controls were ECL8559 [15], and Listeria monocytogenes of porcine origin respectively [16]. However, gene encoding F18 was detected by uniplex PCR using published primers [13], and the PCR positive control for this gene was ECL1033.…”

Listeria spp. contamination in a butcher shop environment and Listeria monocytogenes adhesion ability and sensitivity to food‐contact surface sanitizers

“…According to the recommendations of Djordjevic, Wiedmann, and Mclandsborough, () and Lariviere‐Gauthier et al (), the L. monocytogenes isolates were subjected to adhesion capacity tests. Essentially, 20 μL of an overnight culture of L. monocytogenes was transferred to a well of a microtiter plate containing 130 µL of TSB (Oxoid) and incubated at 37 °C for 24 h. After incubation, the cultures were discarded, and the wells were washed with PBS (pH 7.2) three times to remove non‐adhered cells.…”